Many devices on the market today require batteries for their power source. Each of these devices may impose their own requirements on the battery, for instance, the batteries form factor, voltage and charge delivering capability. There are many examples of devices that require non-standard batteries such as cellular phones and notebook computers. Often the battery is externally attached to the device and become part of its ornamental design. Some devices, such as a family of power tools, share a common battery pack with a proprietary form factor. Allowing a device to only accept a battery pack with a non-standard form factor ensures that batteries used in a device will meet the requirements of the device. For these reasons, and many others, the manufactures of devices will often design a battery (or battery pack) in tandem with the device.
For each specially designed battery, however, a corresponding battery charger generally has to be designed that will accept both the form factor of the battery and charge the battery in a manner that it requires. Since many battery chargers step down line voltage to a low voltage that can be used to charge the battery, the use of line voltage imposes a requirement on the manufacturer that the battery charger be certified safe by a certification authority such as Underwriter's Lab (UL). The battery charger is often designed near the end of the development cycle once the design of the battery is known, even though certification requirements for the battery charger may unnecessarily delay the introduction of the device.
The myriad of configurations of battery chargers provided to accommodate the various known battery shapes, sizes, and load capabilities is potentially burdensome for a user of the device. Unfortunately, because there are so many different types of battery chargers, it is not unusual for a person to own multiple battery charging devices--one being required for each unique battery configuration. This is both expensive for the user and inefficient in space and outlet usage. The cost to the manufacturer for complying with the certification requirements for a battery charger is also unnecessarily expensive and time consuming.
Thus, a need exists for a new battery charging system that reduces the need for a user to buy multiple battery charging devices, reduces the space and outlet usage associated with operating the battery charging device, and reduces the manufacturer's cost and lead time in designing and producing and battery charging devices. The present invention is directed to fulfilling these needs and others as described below.